Pain intensity, disability and depression in individuals with chronic back pain

OBJECTIVES: to measure the pain intensity, identify the disability and depression levels in people with chronic back pain and to correlate these variables. A cross-sectional, descriptive and exploratory study was undertaken at the Pain Treatment Clinic of the University of São Paulo at Ribeirão Preto Hospital das Clínicas, between February and June 2012, after receiving approval from the Ethics Committee at the University of São Paulo at Ribeirão Preto College of Nursing. METHOD: sixty subjects with chronic back pain participated. The instruments used were: the 11-point Numerical Category Scale, the Roland-Morris Disability Questionnaire and the Beck Depression Inventory. To analyze the data, the arithmetic means, standard deviations and Spearman's correlation coefficient were calculated. RESULTS: the findings show that the participants presented high pain, disability and depression levels. The correlation between pain intensity and disability and between pain intensity and depression was positive and weak and, between disability and depression, positive and moderate. CONCLUSION: the study variables showed moderate and weak indices and the mutual correlations were positive.


Introduction
Pain is a multidimensional and subjective phenomenon. Therefore, individuals in pain need to be treated holistic and individually (1) .
For the health professionals to be able to holistically manage pain, a comprehensive assessment of this individual is needed, considering physical, mental, social and spiritual aspects. Therefore, these professionals should understand that pain means an aggravation of one's existence, as not only the physical body, but life in its different dimensions is ill, including the relation with oneself, family, work and leisure (2) .

The American Agency for Healthcare Research and
Quality and the American Pain Society describe pain as the fifth vital sign, which should always be registered at the same time and in the same clinical context as the other vital signs: temperature, pulse, breathing and blood pressure (3) .
Chronic Back Pain (CBP), focused on in this study, can occur due to traumas, mechanical injury, inflammation, infection, among other, and almost all adults have already perceived it at some moment in their life. Its chronicity is defined as it continues for at least three months (4) . Its prevalence levels are high in Brazil, entailing high social and economic costs (4)(5)(6) .
These costs are related to the pain-associated disabilities and to emotional problems like depression, anxiety and despair (7)(8) . Disabilities impose limitations, such as the impossibility to develop professional activities, leave from work, changes in leisure activities and changes in family life (9)(10) .
Depression is the most frequent emotional condition in individuals in chronic pain and there is evidence that it is related to the pain intensity (11)(12)(13)(14) .
In that context, this study emerged as a scientific contribution proposal to better understand factors associated with CBP, such as pain intensity, disability and depression; it provides support for health professionals to better perceive the changes the CBP causes and the importance of assessing these factors for the purpose of pain management. Also, it provides support to choose more effective therapeutic approaches for individuals with CBP.
The objectives in this study were: to measure the intensity of perceived CBP; identify the disability for activities of daily living; identify the depression levels and establish correlations among the study variables, as these can directly influence the activities of daily living and work activities, affecting the quality of life.

Ethical considerations
The project received approval from the Research

Participants
The research participants were individuals under treatment for CBP. The data were collected between February and June 2012. The following inclusion criteria were used: being older than 18 years of age and having a medical diagnosis of non-oncologic CBP (pain for more than 3 months). The exclusion criteria were: individuals with inability to rationalize and changes in physical and/or cognitive functions that did not permit the data collection.

Place
The data were collected at the Pain Treatment Clinic of the University of São Paulo Medical School Hospital das Clínicas (HCRP-USP).

Instruments
To achieve the objectives, a questionnaire was used that contained the items to collect sociodemographic and economic data, questions regarding the perceived pain, the Roland-Morris Disability Questionnaire (15) and the Beck Depression Inventory (16) . The Roland-Morris Disability Questionnaire and the Beck Depression Inventory are freely accessible.
The pain intensity was assessed using the Numerical Categorical Scale (0 to 10 points), with 0 indicating "no pain", 10 "maximum pain", while the other scores, from 2 to 9, indicate intermediary perceived pain levels.

Disability was assessed using the Roland-Morris
Disability Questionnaire, which is a specific instrument to assess disability in subjects with CBP, adapted and validated for the Brazilian culture (15) . This instrument contains 24 assertions about the activities of daily living that indicate disabilities the pain provokes, using the phrase "because of my back...". The questionnaire score is calculated using the total number of questions marked as "yes", with a range from 0 to 24, in which zero corresponds to the absence of disability and 24 to 571 www.eerp.usp.br/rlae Garbi MOSS, Hortense P, Gomez RRF, Silva TCR, Castanho ACF, Faleiros Sousa FAE.
severe disability, and results higher than 14 indicate significant disability (17) .
Depression was assessed using the Beck Depression Inventory (BDI), validated for the Brazilian culture.
This instrument consists of 21 items scored from 0 to 3, reflecting the intensity of the symptom. The score ranges from 0 to 63 and, the higher the score, the higher the perceived depression level. For non-diagnosed samples, the guidelines are different. Scores superior to 15 are recommended to detect dysphoria and the term "depression" should only be used for individuals scoring more than 20, preferably with a concomitant clinical diagnosis (16) .

Procedures
A cross-sectional, descriptive and exploratory research was undertaken.
First, the subjects were selected through their medical file. The analysis of the patient histories served to identify the CBP. Next, after the participants were invited and agreed to participate, the data collection started with the use of the abovementioned instruments.

Analysis of the results
To analyze the sociodemographic data and the data related to pain, depression and disability, descriptive The correlations among pain intensity, disability and depression were calculated using Spearman's correlation coefficient, which quantifies the degree of dependence between two variables, using a single figure to describe the relation among them. The significance level was set at 0.01 (18) .

Results
The participants were sixty individuals with CBP.  The correlations were calculated using Spearman's correlation coefficient and the significance level was 0.01. The correlation found between pain intensity and disability was positive and weak (0.232). Between the variables pain intensity and depression, a weak and positive correlation was also observed (0.166).
The correlation between the variables disability and depression was moderate and positive (0.362).

Discussion
As regards the participants' perceived pain intensity, the mean score was 7.38 points and 55% of the interviewees showed a pain intensity of 8.0 points or higher; hence, it can be considered that the study subjects showed high levels of pain intensity. Some Brazilian and international authors also found CBP patients with high levels of pain intensity (7,9,(19)(20) .
As regards the disability, assessing using the RMDQ (0-24 points), the mean score was 19.87 points, suggesting that the individuals in this sample presented high levels of functional disability. In Brazil and abroad, there are studies showing similar results in CBP patients (12)(13)(14)19) .
Concerning depression, assessed using the BDI (0 to 63 points), the mean score in the study sample was 24.98 points, suggesting some level of depression.
The existing correlations between pain intensity and disability and between pain intensity and depression were weak and positive. Therefore, it is considered also observed these correlations (7,9,14,19) .
Disability prevents people from doing activities they used to, such as housework, sports, social interaction etc., allowing depression symptoms to appear. The opposite can also be true, that is, depressed subjects tend to get more isolated and lose motivation to engage in any kind of activity.
In this and other studies mentioned below, the researchers' great concern with assessing various aspects of CBP is observed, identifying indices related to the impact of pain in daily life. This is extremely important to further understand such a complex phenomenon and, thus, to formulate pain management proposals.
Researchers have developed a study to assess  (8) .
In a study, the researchers observed that depression appeared in 52% of CBP subjects, with a substantial relation between depression and CBP 573 www.eerp.usp.br/rlae Garbi MOSS, Hortense P, Gomez RRF, Silva TCR, Castanho ACF, Faleiros Sousa FAE.
cases. The authors suggest that the large majority of the subjects suffering from CBP experience emotional problems like depression, anxiety and despair, besides being exposed to determining socioeconomic factors.
Therefore, these components need to be identified with a view to a more complete and effective approach in the management of CBP (9) .
In a study of subjects with CBP, the researchers assessed depression using the BDI (11.86), disability using the RMDQ (12.7) and coping strategies and pain and request social help. It was also observed that the strategies to cope with the chronic pain are related with the pain control beliefs, depression and disability (22) .
In another study, researchers studied the correlation between disability (Oswestry Disability As observed, there was no correlation between sleep quality and physical activity in the three groups and no effect of physical activity on disability, depression and sleep quality was observed in group III (23) .
Researchers developed a study and found a mean disability score of 8.64 points on the RMDQ in CBP patients. After assessing the results, they concluded that the individuals who felt back pain over a longer period and had low self-efficacy scores presented less effective clinical outcomes. The authors associated the back pain with psychological factors and observed that disability was associated with a negative perception about the consequences of the disease, low self-efficacy and depression (13) .
In one study, the authors found a mean pain intensity level of 7.8 points, with 80.7% of the patients showing moderate to severe disability and 36.7% depression levels. Three factors were found related to the disability: lack of paid work, low self-efficacy and depression. They also observed a higher disability prevalence among the subjects with intense pain, prolonged pain, depressive symptoms, fatigue, low self-efficacy, high levels of fear and avoidance of pain (7) .
The researchers observed that the subjects with depression symptoms had a 1.2 times higher chance of disability than the subjects without this symptom.
Therefore, treating depressive symptoms is effective to minimize the disability. Pain-related disability impairs different aspects of daily life and provokes mental suffering (7) .
In a study involving participants with CBP, the researchers observed high levels of pain intensity, disability and depression. The results showed that disability and depression revealed a weak and positive correlation, suggesting that disability increases with depression or vice-versa. As regards the physical function, it was observed that, when it decreases the pain intensity, anxiety, depression and fear increase, while the quality of life decreases when the pain intensity and fear increase (19) .
A study was conducted to examine the influence of catastrophization and other psychological variables on pain and disability in 78 subjects with CBP. They observed in the results that the CBP patients obtained a mean score of 11.6 points on the RMDQ and 5.3 points on the VAS, concluding that perceived pain and disability are strongly correlated with the catastrophization of pain, fear and depression (12) .
In the abovementioned studies (7,(12)(13)19)  the family history are also related with the CBP and all of these factors can change the CBP from mild to moderate (10) .
Individuals facing difficulties to accomplish activities of daily living and who are unable to work tend to get distanced from social life and avoid leisure activities. Social isolation and the avoidance of painrelated activities can reduce the self-efficacy and increase the chance of developing depressive and disability symptoms (7) .
In a study to analyze the relation among psychological factors, physical performance and disability, it was observed that the mean pain intensity score found was 5 points, the mean disability score (RMDQ) 12.6 points and the mean depression (BDI) score 7.3 points.
No correlation was found among disability, depression and physical performance, differently from the present study (14) .
The researchers in this study raise the hypothesis that the correlation may not have existed, differently from several other studies, due to the sample characteristics, such as the subjects' mean age (38.5 years), the mean pain intensity (5) and the mean duration of the perceived pain (13 months). When comparing these data with the present study, a difference in these characteristics is observed, as the present sample shows a higher mean age (54.8 years), pain intensity (7.38) and duration of perceived pain (108 months).
Therefore, it is considered necessary to assess